Bad data at Bon Tempe Lake

December 29, 2009 at 12:00 PM in: maps

Got the dynamic range right on the shaded relief. (Click image for 1024x1024 version):

Alpine Lake and Bon Tempe Lake

Alpine Lake and Bon Tempe Lake (CC-by-SA license)

I've spent several days trying to figure out why the roads in the MRLC land cover data don't line up with the OpenStreetMap roads. The creeks (from NHD), elevation (from 10m NED), and roads all seem to line up in a way that matches aerial photographs. I double checked all projections, installed the latest versions of everything, lots of web research, no clue what's going on.  The roads seen in the landcover data are the right shape, they're just off in position. But they're off in position by a variable amount.

I finally noticed that the landcover doesn't even agree with itself! There are places where the landcover data indicates a road crossing open water and there is obviously no bridge. The dam on Bon Tempe lake shows that the vegetation and water are correctly aligned with OpenStreetMap, but the pink line for the road crossing the dam doesn't line up with the other landcover pixels.

Is this a known problem with MRLC?

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